A passive optical network (PON) is a point-to-multipoint fiber-optic network, in which unpowered optical splitters are used to enable a single optical fiber to service multiple premises, typically 16-128 homes. Reference is made to FIG. 1, which is a simplified diagram of a prior art PON 100. As seen in FIG. 1, PON 100 includes a central office node, referred to as an optical line terminal (OLT) 140, a number of user nodes, referred to as optical network units (ONUs) 120, which are near user premises 130, and fibers 150 and splitters 160 between them.
Data is transmitted within PON 100 in packets referred to as data frames. Downstream signals (i.e., signals transmitted from left to right in FIG. 1) originate from network services, such as an Internet service 110A, a voice over IP service 110B, a cable TV service 110C and other such services 110D. The downstream signals are broadcast to all premises 130 that share a single fiber. Bandwidth for upstream signals (i.e., signals transmitted from right to left in FIG. 1) is allocated by time-division multiplexing among ONUs 120. Current PONs 100 operate at 1 Gbit/s and 2.5 Gbit/s rates, and 10 Gbit/s PONs will be available in the near future.
A drawback of conventional PONs 100 is the large amounts of power that they consume. Moreover, as traffic rates in a PON increase, the power consumption of the PON also increases. As such, as PONs improve to operate at higher rates, the need to reduce their power consumption is ever more pressing.